Those sad and emotional scenes overshadowed the gritty triumph of Canberra mare Single Gaze ($3.30 fav) who won the Group II PJ O'Shea Stakes (2200m) at Doomben by 1-1/4 lengths from Queenslander Rudy ($6).

High Church ($4.20) never threatened and was beaten 1-3/4 lengths into third.

Cylinder Beach looked like the winner in the home straight as he went up to challenge Single Gaze before breaking down in front of shocked racegoers.

Byrne came back and wiped away tears, hugging connections and said simply, "I'm so sorry".

While trainer Nick Olive was happy to grab a Group II win with his classy mare, his thoughts were with the trainer and connections of Cylinder Beach.

The Queensland gelding was unable to be saved.

"I hate to see that sort of thing happen, I am so sorry for the connections and the trainer," Olive said.

"I will say my mare has got the heart of a tiger. We have stuck with (jockey) Kathy O'Hara and I am so pleased we have."

Single Gaze is now likely to be spelled.

The connections of Cylinder Beach had already been through an emotional journey as original owner Chris Lees died of brain cancer in 2015.

Lees' wife Tracey remained in the ownership of Cylinder Beach, named after Chris Lees' favourite holiday spot on Stradbroke Island.

Preferment ($4.60) was disappointing in the PJ O'Shea Stakes, leading easily but fading to finish fourth and be beaten 5.5 lengths. He has now gone 433 days without winning.

Winx's half-brother El Divino was humanely euthanised on Friday after suffering an irreparable injury in a light piece of work at Ararat.

The Darren Weir stable confirmed the four-year-old stallion fractured a cannon bone in the last 200m of an 800m gallop, from which jockey John Allen emerged unscathed and was able to fulfil his engagements in the jumpouts that followed.

A winner of the Group 2 Kindergarten Stakes (1100m) when in the care of Gai Waterhouse and Adrian Bott, the son of Snitzel was placed in two of his seven starts for Weir, including a narrow defeat to stablemate Brave Smash in the Listed Chandler McLeod Stakes (1200m) earlier in the season.

He won 12 races - three of them at Group 1 level - but Naturalism will be best remembered for the race he didn't win.

Naturalism, who died on Friday at the age of 29 at Meringo Stud on the NSW south coast, burst onto the scene in 1992 when he clashed several times in the autumn classics in Sydney with Kiwi champion Veandercross.

Six months later, Naturalism was considered the country's best weight-for-age horse and was sent out the even-money favourite in the Cox Plate.

It turned out to be a Cox Plate special with the remarkable Super Impose taking the event from the likes of Let's Elope and Better Loosen Up, but not so for Naturalism and his jockey Mick Dittman as they parted ways near the 600-metre mark.

The Australian breeding scene has lost one of its great stallions with the news of the death of Encosta De Lago at the age of 25.

Coolmore Australia confirmed the news on Saturday, claiming the son of Fairy King will be remembered as "one of the greatest Australian-bred sires of all time".

Encosta De Lago sired 26 individual Group 1 winners worldwide with his progeny amassing more than $180 million in prizemoney.

His death comes on the heels of the retirement of one of his most favourite sons Chautauqua, a six-time Group 1 winner. Other champion performers by the stallion include Alinghi, English and Racing To Win.